1. Field of the Invention
The present invention generally regards the holding of medical devices during manufacture to enable the application of therapeutic and/or protective coatings. More specifically, the present invention provides medical device holders that securely retain medical devices during the application of a coating while minimizing compressive and tensile forces applied to the medical devices and disruptions to the coating due to holder blockage of coating deposition. The invention discloses an improved device that may improve coating uniformity by reducing shadowing from the frame of the medical device holder when applying coatings to medical devices.
2. Background
A wide variety of medical devices have been developed as medical implants and are used for innumerable medical purposes, including the reinforcement of recently re-enlarged lumens, the replacement of ruptured vessels, and the treatment of disease such as vascular disease by local pharmacotherapy, i.e., delivering therapeutic drug doses to target tissues while minimizing systemic side effects. Such localized delivery of therapeutic agents has been proposed or achieved using medical implants which both support a lumen within a patient's body and place appropriate coatings containing therapeutic agents at the implant location.
The term “medical device” as used in this application includes stents, catheters, synthetic veins and arteries, artificial valves or other similar devices with a hollow or open center portion amenable to coating on the holder. For clarity, understandability and by way of example, the term “stent” in this application is used interchangeably with the term “medical device”. The delivery of expandable stents is a specific example of a medical procedure that involves the deployment of coated implants. Expandable stents are tube-like medical devices, typically made from stainless steel, tantalum, platinum or nitinol alloys, designed to be placed within the inner walls of a lumen within the body of a patient. These stents are typically maneuvered to a desired location within a lumen of the patient's body and then expanded to provide internal support for the lumen. The stents may be self-expanding or, alternatively, may require external forces to expand them, such as by inflating a balloon attached to the distal end of the stent delivery catheter.
Because of the direct contact of the stent with the inner walls of the lumen, stents have been coated with various compounds and therapeutic agents to enhance their effectiveness. These coatings may, among other things, be designed to facilitate the acceptance of the stent into its applied surroundings. Such coatings may also be designed to facilitate the delivery of one of the foregoing therapeutic agents to the target site for treating, preventing, or otherwise affecting the course of a disease or tissue or organ dysfunction.
The mechanical process of applying a coating onto a stent may be accomplished in a variety of ways, including, for example, the spraying of the coating substance onto the stent. While applying the coating to the stent, there is a need to contact the stent with the spray to ensure an even, intact, robust coating of the desired thickness on the stent.